<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        * {
            margin: 0;
            padding: 0;
        }
        html { background-color: #CCC; }
        .container {
            margin: 30px auto;
            width: 90%;
        }

        .menu, .menu ul {
            list-style: none;
            padding: 0;
            margin: 0;
        }
        .menu {
            height: 58px;
        }
        .menu li {
            background: -moz-linear-gradient(#292929, #252525);
            background: -ms-linear-gradient(#292929, #252525);
            background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #292929), color-stop(100%, #252525));
            background: -webkit-linear-gradient(#292929, #252525);
            background: -o-linear-gradient(#292929, #252525);
            filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#292929', endColorstr='#252525');
            -ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr='#292929', endColorstr='#252525')";
            background: linear-gradient(#292929, #252525);

            border-bottom: 2px solid #181818;
            border-top: 2px solid #303030;
            min-width: 160px;
        }
        .menu > li {
            display: block;
            float: left;
            position: relative;
        }
        .menu > li:first-child {
            border-radius: 5px 0 0;
        }
        .menu a {
            border-left: 3px solid rgba(0, 0, 0, 0);
            color: #808080;
            display: block;
            font-family: 'Lucida Console';
            font-size: 18px;
            line-height: 54px;
            padding: 0 25px;
            text-decoration: none;
            text-transform: uppercase;
        }

        .menu li:hover {
            background-color: #1c1c1c;
            background: -moz-linear-gradient(#1c1c1c, #1b1b1b);
            background: -ms-linear-gradient(#1c1c1c, #1b1b1b);
            background: -webkit-gradient(linear, left top, left bottom, color-stop(0%, #1c1c1c), color-stop(100%, #1b1b1b));
            background: -webkit-linear-gradient(#1c1c1c, #1b1b1b);
            background: -o-linear-gradient(#1c1c1c, #1b1b1b);
            filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#1c1c1c', endColorstr='#1b1b1b');
            -ms-filter: "progid:DXImageTransform.Microsoft.gradient(startColorstr='#1c1c1c', endColorstr='#1b1b1b')";
            background: linear-gradient(#1c1c1c, #1b1b1b);

            border-bottom: 2px solid #222222;
            border-top: 2px solid #1B1B1B;
        }
        .menu li:hover > a {
            border-radius: 5px 0 0 0;
            border-left: 3px solid #C4302B;
            color: #C4302B;
        }

        .submenu {
            left: 0;
            max-height: 0;
            position: absolute;
            top: 100%;
            z-index: 0;

            -webkit-perspective: 400px;
            -moz-perspective: 400px;
            -ms-perspective: 400px;
            -o-perspective: 400px;
            perspective: 400px;
        }
        .submenu li {
            opacity: 0;

            -webkit-transform: rotateY(90deg);
            -moz-transform: rotateY(90deg);
            -ms-transform: rotateY(90deg);
            -o-transform: rotateY(90deg);
            transform: rotateY(90deg);

            -webkit-transition: opacity .4s, -webkit-transform .5s;
            -moz-transition: opacity .4s, -moz-transform .5s;
            -ms-transition: opacity .4s, -ms-transform .5s;
            -o-transition: opacity .4s, -o-transform .5s;
            transition: opacity .4s, transform .5s;
        }
        .menu .submenu li:hover a {
            border-left: 3px solid #454545;
            border-radius: 0;
            color: #ffffff;
        }
        .menu > li:hover .submenu, .menu > li:focus .submenu {
            max-height: 2000px;
            z-index: 10;
        }
        .menu > li:hover .submenu li, .menu > li:focus .submenu li {
            opacity: 1;

            -webkit-transform: none;
            -moz-transform: none;
            -ms-transform: none;
            -o-transform: none;
            transform: none;
        }

        .menu li:hover .submenu li:nth-child(1) {
            -webkit-transition-delay: 0s;
            -moz-transition-delay: 0s;
            -ms-transition-delay: 0s;
            -o-transition-delay: 0s;
            transition-delay: 0s;
        }
        .menu li:hover .submenu li:nth-child(2) {
            -webkit-transition-delay: 50ms;
            -moz-transition-delay: 50ms;
            -ms-transition-delay: 50ms;
            -o-transition-delay: 50ms;
            transition-delay: 50ms;
        }
        .menu li:hover .submenu li:nth-child(3) {
            -webkit-transition-delay: 100ms;
            -moz-transition-delay: 100ms;
            -ms-transition-delay: 100ms;
            -o-transition-delay: 100ms;
            transition-delay: 100ms;
        }
        .menu li:hover .submenu li:nth-child(4) {
            -webkit-transition-delay: 150ms;
            -moz-transition-delay: 150ms;
            -ms-transition-delay: 150ms;
            -o-transition-delay: 150ms;
            transition-delay: 150ms;
        }
        .menu li:hover .submenu li:nth-child(5) {
            -webkit-transition-delay: 200ms;
            -moz-transition-delay: 200ms;
            -ms-transition-delay: 200ms;
            -o-transition-delay: 200ms;
            transition-delay: 200ms;
        }
        .menu li:hover .submenu li:nth-child(6) {
            -webkit-transition-delay: 250ms;
            -moz-transition-delay: 250ms;
            -ms-transition-delay: 250ms;
            -o-transition-delay: 250ms;
            transition-delay: 250ms;
        }
        .menu li:hover .submenu li:nth-child(7) {
            -webkit-transition-delay: 300ms;
            -moz-transition-delay: 300ms;
            -ms-transition-delay: 300ms;
            -o-transition-delay: 300ms;
            transition-delay: 300ms;
        }
        .menu li:hover .submenu li:nth-child(8) {
            -webkit-transition-delay: 350ms;
            -moz-transition-delay: 350ms;
            -ms-transition-delay: 350ms;
            -o-transition-delay: 350ms;
            transition-delay: 350ms;
        }

        .submenu li:nth-child(1) {
            -webkit-transition-delay: 350ms;
            -moz-transition-delay: 350ms;
            -ms-transition-delay: 350ms;
            -o-transition-delay: 350ms;
            transition-delay: 350ms;
        }
        .submenu li:nth-child(2) {
            -webkit-transition-delay: 300ms;
            -moz-transition-delay: 300ms;
            -ms-transition-delay: 300ms;
            -o-transition-delay: 300ms;
            transition-delay: 300ms;
        }
        .submenu li:nth-child(3) {
            -webkit-transition-delay: 250ms;
            -moz-transition-delay: 250ms;
            -ms-transition-delay: 250ms;
            -o-transition-delay: 250ms;
            transition-delay: 250ms;
        }
        .submenu li:nth-child(4) {
            -webkit-transition-delay: 200ms;
            -moz-transition-delay: 200ms;
            -ms-transition-delay: 200ms;
            -o-transition-delay: 200ms;
            transition-delay: 200ms;
        }
        .submenu li:nth-child(5) {
            -webkit-transition-delay: 150ms;
            -moz-transition-delay: 150ms;
            -ms-transition-delay: 150ms;
            -o-transition-delay: 150ms;
            transition-delay: 150ms;
        }
        .submenu li:nth-child(6) {
            -webkit-transition-delay: 100ms;
            -moz-transition-delay: 100ms;
            -ms-transition-delay: 100ms;
            -o-transition-delay: 100ms;
            transition-delay: 100ms;
        }
        .submenu li:nth-child(7) {
            -webkit-transition-delay: 50ms;
            -moz-transition-delay: 50ms;
            -ms-transition-delay: 50ms;
            -o-transition-delay: 50ms;
            transition-delay: 50ms;
        }
        .submenu li:nth-child(8) {
            -webkit-transition-delay: 0s;
            -moz-transition-delay: 0s;
            -ms-transition-delay: 0s;
            -o-transition-delay: 0s;
            transition-delay: 0s;
        }
    </style>
</head>
<body>
<div class="container">
    <ul class="menu">
        <li><a href="#">主页</a></li>
        <li><a href="#">菜单一</a>
            <ul class="submenu">
                <li><a href="#">子菜单A</a></li>
                <li><a href="#">子菜单B</a></li>
                <li><a href="#">子菜单C</a></li>
                <li><a href="#">子菜单D</a></li>
                <li><a href="#">子菜单E</a></li>
                <li><a href="#">子菜单F</a></li>
                <li><a href="#">子菜单G</a></li>
                <li><a href="#">子菜单H</a></li>
            </ul>
        </li>
        <li class="active"><a href="#s2">菜单二</a>
            <ul class="submenu">
                <li><a href="#">子菜单A</a></li>
                <li><a href="#">子菜单B</a></li>
                <li><a href="#">子菜单C</a></li>
                <li><a href="#">子菜单D</a></li>
                <li><a href="#">子菜单E</a></li>
                <li><a href="#">子菜单F</a></li>
                <li><a href="#">子菜单G</a></li>
                <li><a href="#">子菜单H</a></li>
            </ul>
        </li>
        <li><a href="#">菜单三</a>
            <ul class="submenu">
                <li><a href="#">子菜单A</a></li>
                <li><a href="#">子菜单B</a></li>
                <li><a href="#">子菜单C</a></li>
                <li><a href="#">子菜单D</a></li>
                <li><a href="#">子菜单E</a></li>
                <li><a href="#">子菜单F</a></li>
                <li><a href="#">子菜单G</a></li>
                <li><a href="#">子菜单H</a></li>
            </ul>
        </li>
        <li><a href="#">菜单四</a></li>
        <li><a href="#">返回教程</a></li>
    </ul>
</div>
</body>
</html>